Two-ply cinematograph positive film



N O T N R O. H T E ,l gw. 2 9 1 5, m

TWO-FLY QINEMTOGRAPH POSITIVE FILM 2 Sheets-Se-et l Filed May 4, 1925 Tige).

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TWO-FLY CINEMATOGRAPH POSITIVE FILM Patented June 5, 192s.

UNITED STATES- i 1,672,352 .PATaN'rl OFFICE.

JOHN THORNTON, F HAMPSTED, LONDON, ENGLAND.

Two-FLY CINEMATGRAPH roem FILM.

Appia-ation flied May i, 192s, serial No. 106,731, nain' Great mmm )man 1a, 192e. y .y

This invention relatesio an improved Ic inematograph two-color film of positive pictur'es, of the type built up from two thin films cemented together back-to-.back, .the images upon one outer facevof the completed .film being of orange-red coloring and those upon the opposite outer face of bluegreen coloring, one of the images being reversed in relation to the other; and to an improved` process of producing such film with silver sensitizing; without having to creeping and miizing ofthe two` dyes; with,

out forming a softened weakened hinge longitudinally of the strip to-enable it to be folded; without folding the strip; without the use' of methyl-alcohol to soften the' cel' luloid backs; and without need for cementing the `two thinfilmstogether before development; all of which featuresare used in theproduction of another two-color film of 4the two-.ply type, but are not used in the present lnvention.

The characteristic features of the present inventiontherefore comprises the following,

'ble-width sensitized film of half standard thickness, orange-red on one'half and blue-,

used or operating in combination (l) Ready-colored film-material, of

(2) Double-width, with two parallel col-4 ored stripes,

(3) Sensitized with silver for -gapid print- Ulg (4) Side-byside development, folding or cementing the film;

(5) Insoluble: printed margins, retaining full strength and thickness of film-material; (6) Sever-ing the strip -after development and-finishing and before cementing;

(7) True width without folding or trim ming;

(8) Joint formed by two layers of slow. drying cement; 1

(9) Registration by lspeci-al registration perforations made before printing;

(10) Traction by additional perforations made after printing, finishing and cementwithout infr' L(l1) Imagepair identification by numbers; y

(12) Varnishing the finished print.

lAccording to the invention the positivesv are printed upon a double-width strip 'of' ready-colored film-material comprising two parallel stripes of orange-red and blue-green coloredl'colloid, carriedx upon and amalgamated by means of an adhesive substratum with-a double-width support of trans'- parent celluloid or like waterproof material,

the 'thin film having `-a. thickness approXi-. mately half the ultimate thickness of a com,-

pleted film-positive, the. colloid layer be-l ing sensitized with silver salts, preferably7` as. a gelatinsilver emulsion. This film-material is printed by exposure fromthe back through the celluloid support and' through a suitable printing-clich of negative character, to produce images.

The colloid is gelatine, and thecoloring a positive with relief sol matter may comprise pigments or dyes, but

dyes are preferred and are suitably inordanted to prevent their washing out.

The film-material is printed, developed, and vdried whilst in its double-width form, after which it is` longitudinally severed to form two films that are subsequently cemented together back-to-backto form the completed single-widthA film-positive.

The accompanying drawings illustrate the invention in which drawings Fig. 1 shows a strip of ready-colored dougreen on the other half. f Fig. 2 shows the same iilm perforated before printing with one hole for each picture component for registration purposes only while printing, assembling, and cementing. Fig.V 3 `shows a double-width negative strip having the conventional design of a square, the image for one negative being reversed. The negative on the right represents orange-red and that on theleft bluegreen. Two ysingle-width negatives may be used side by side instead of one doublematerial vprovided with a temporary paper i backing which acts as a strengthening strip' during the printing and developing operations.

Fig. 1l shows means for uniting the two films together.

The thickness of the various layers are approximately as follows Tli'e'celhiloid layer 1, of an inch.

The substratum 2,010 00 of an inch.

` 1 The colored sensitizedv colloid layei 1000 of an inch.

10u00 of an inch, but in the various figures the printed colloid-relief-layer is shown enlarged out of proportionto the thickness The temporary paper reinforcement A of the other layers for the sake of clearness.v

Fit/immaterial and sensitizing process. I The film-material may be of the type com- Aprising a celluloid layer, a substi'atum layer, a colored colloid layer, and a temporary reinforcing strip of paper attached to -its colored face forgiving extra strength to the film during the printing and developing processes, as described in my specificatio'n Serial No: 35761, June 8th, 1925; or

it may be of the non-reinforced ordinary type film-materiali comprising a celluloid layer, a substiatum layer, and a colored l colloid layer, as described in my specification Serial No. 35,760 June 8th, 1925.111 both forms the film-material is provided with two parallel strips of colloid ready colored A with vthe correct pair of colors, and with the correct quantity of color in each, that will produce a. finished picture having properly balanced and proportioned colors without any need for the usual troublesome dyeing of the images or adjusting the colorings by the printer after the` film has been exposed and developed, which are necessary with other processes. These two colors are orange-red and blue-green, but instead red and blue may be substituted upon condition that after the film has been developed a` yellow .dye isapplied all over 'the film in order to convert the red images into orangered andthe blue images into blue-green.

The film-material is sensitized with salts of silver by any of the linown methods, but the method preferred is to use a gelatinesilver-bromide emulsion of the usual type. oi a gelatino-silver-chloride emulsion, the emulsion being coat-ed on to an adhesive sub- 'stratum previously coated on to the -cellulose support and dried this substratum effecting a perfect. union or amalgamation of the support and emulsion, the colors being incorporated in the emulsion layer as aforesaid. j

Negatives, or printing clichs.

The lnegatives used for printing may be either the original negatives or printingclichs reproduced therefrom, and the two component negatives orV clichs may be forined -as two parallel rows vupon adoublewidth strip, or` two separate single-width negative-strips may be used side by side.

Printing the positives.

Printing ofthe double-Width'strip isA ef- .l

fected Ain the same manner as in printing ordinary non-colored film, except that more exposure is necessary, which is preferably attained by using a more powerful lamp in the printing-machine. The printing-machine is also of standard type except that it is made to take a film of double-width.

- Printing must be effected through the back of the film support, not from the face side, the negative also being reversed so that the rimages are right way about. That is to say, the celluloid sides of both films are towards each other during the operation of printing. 'v

Printing can bev effected either by contactor by the projection method, the latter being preferred. The negative film therefore passes through one machine in front of a lamp and the images are projected by means of either one lens (or a pair of lenses) onto the positive film, which passes through another machine placed opposite. the two machines being mounted upon a baseplate and geared to synchronize, the lens or lenses being mounted between. The light beams are made to take parallel form in order to ensure sharp images.

Identifying v componen ts.

To guard against any possibility of' mistakes in correctly assembling the two component images of the same picture, identifilcation numbers may be printed on both illu/gifts of full strength and thickness.

ln other inventions where images are and before coloring, which had the effect of reducing the thickness 'of the finished cemented film at the perforated margins, thus considerably reducing the strength of the i filmat the very place where it most needed strengthening. vThese bare margins formed dams, which prevented creeping andmixing if the two dyes during thev process of dyeing the two sides of the printed land cemented film. I

A feature of the present invention is that 'this objection is removed byleaving the full thickness of gelatine covering both margins of both component strips, so that when the two films are cemented together'the completed filmepositive will lfave full thickness and full strength at the two margins where most needed. This is rendered possible -because it is not required to dye the two sides of the print after, completion as they are al-` `ready colored.

In the ordinary course of printing films of the relief type the margins are 4covered by opaque parts ofthe printing-cliche, and

'receive no exposure and subsequent treat ment to insolublize them, and therefore dissolve away during the hot-water development.l But in the present invention these -margins are given a separateand very complete exposure and subsequent treatment, to render them completely insoluble, 'by exposing them to the printing lamps in such man' ner that the already exposed image parts are protected by an opaque covering mask and the' margins are left uncovered and exposed to the full light of the lamps thus produc-l f ing printed margins which ondevelopment remain solid, insoluble, and of full'thickness.

A characteristic feature therefore of th'i invention-is that the margins of the printed films are always rendered insoluble and opaque or fully-colored, and are always left finished with the full thickness and strength of. the original hlm-material.

Developing the posz't/ves.

film progresses continuouly through the machine.

Any suitable known developer may be used, such as metol-hydrokinone, pyrogallicacid, and others.

After development the film is treated in an oxydizing and bleaching bath of the usual type, by which the gelatine is hardened where in contact with the grains of metallic silver and in direct ratio to the amount of i 'formed in relief a characteristic .feature'lliii'ssuch silver .reduced the developer. These been that the margins of the film were bared; and freed fromgelatine after development portions `of. -the 'gelatine where Vthere is no deposit remain soft and solu- 'The aim istria-aged bath A@if seinem hyposulphite tov which may', be added affsma'll proportion of an'L alkaline ferricyanide suchl as potassium-ferifianide',,andgthe whole "of the silver (expe @and unexposed) is dissolved out of lther-film,'leaving behind a transparent b ut colored gelatine' body having images of hardened insoluble gelatine and other parts that remain soft andsoluble.

The film isne'xt yfdriedto complete the hardening process, after which it is treated in a bath which is a solvent of soft gelatine. This may be liot water, or. al cold strong s0- lut'ion of a bichromate salt, such as vsodium bichromate, with or without'the addition of a little acetic acid,`o r any other -of the various solvents of gelatine. soft gelatine has been dissolvedand washed -away a film is left with two parallel rows of images in relief, one of orange-red colored gelatine and the other of blue-green 'colored gelatine, and without silver or any other light-obstructing agent.

Development is nowcomplete. No other operations are necessary. No subsequent dyeing of the images is required The film cementing operations.

.The entire operations of developing and drying maybe effected by. any suitable type of machine, oneconvenient form'beingthat described in my Patent No. 1,173,895.

is finally dried and is then ready for the Ceimentzng after developing .and yin'ishag.

In other inventions 4where images vare formed in relief a characteristic feature has been that. thetwo films were cemented together back=tqback (cellulose-to-celluldse) immediately after printing and beforeridevelopment, in order that the images `u pon opposite sides of the central support'could be developed simultaneously in a vhcfitwvater bat-h. Theywere not dyed until afte development, and Lthen each side was dyed separately..

But in the present invention the two films are printed, developed, washed, finished and dried whilst in their double-width form, and

are not severed, superimposed and cemented until the whole Vof these several operatlons have been completed'. This method presents l many advantages in manufacture, one` of rwhich is that the wet prints vare not injured upon their faces by Contact with the numer-l ous sprockets and other mechanism of the developing machine, but on the contrary are maintained face 'outwards with onlyv the back of the celluloid support in contact with the machinery until thelast printing and developing operation has been finished and the filmfimages dried.

When lall the vlll' Produc/ng toit/hout AZongritudz'mzl weakening or folding.

The film was then unfolded and laid as fiatv as possible in order that .it could be printed by contact with the printing clich. Next 1t was again folded and cemented celluloid-tocelluloid prior to development, yfand. finally the folded edge was cut away bya trimming machine. 'lhe objections to such a system are that thefilm-material needs to-.be wider to allow for trimming, and has to be reduced -in thickness at the fold by the application of a partial solvent in order to make the film more pliable at the hinge, so that it can be folded more sharply, and also to `enable it to be refoldedor unfolded readily. This process has to be carried out whilst' the film is sensitive, and before printing; and the treatment of sensitive film in this manner is objectionable in many ways as well as rendering the film liable to distortion' owing to the solvent-produced hinge. l In the present invent-ion Inone of these objections apply,-becaus'e the film 1s never folded but is perforated printed5dcveloped. treated and dried and also longitudinally severed whilst in its original flat condition, and the two sections arealivays true to width, need no trimming, aref without any liability to distortion, and the perforations are capable of accurately superimposing and registering. Separate-registration and traction perforations.

The perforations may comprise the usual four holes per margin per picture` which means lsixteen holes for the pair. But l prefer to perforate the film before printing with only one hole per complete picture for registration purposes only. This means that two adjacent holes are formed in the central margin of thedouble-width film between the two rows of section pictures, one for each picture-component` and when the two severed single-width films arc superimposed and cemented together these two holes coincide in accurate register and form only one hole in onel margin of the completed picture. The united strip is nextI passed through a perforating machine which punches the set of eight holes per picture for traction pur-4 l poses, four in each margin, using the hole already made as a pilot hole from which to work in positioning the remaining holes. This'pilot hole may form one of the set/vof eight. Any other desirednumber .of holes or type of perforations may be used instead of the usual standard eight. This system is described in specification of my application Serial No. 66,605 filed November' 5, 1925, and is particularly well suited for use in the form of lilm comprising the present invention.

Uniting by two .slow-drying thin Zay/ors of cellulose.

After printing and finishing therdouble-n uniform for both sections upto this last stage.

vIn other inventions it has been proposed to unite two (zelluloid-films by softening their hacks with methyl-alcohol, in order to effect a quiclmmion by employing a'solvent that will speedily evaporate. It is well-known by those versed in the art of film manufacture that the quicker a solvent evaporates the less secure will be the union of two cellulose faces joined by its aid.

lln carrying out the Ajointing portion of this invention l therefore do not attempt to make a quick joint by use of a quicklyevaporating solvent of the cellulose supports, but on the contrary l use a slow-drying cement of cellulose compositionV containing a heavy solvent that will not dry too rapidly. rllhe cement is preferably applied to the backs of the two films (whilst they are suitably supported and carried) by meansof spreading knives. scrapers, or `rollers that will apply an extremely thin measured layer of definite thickness of the thick non-flow- :tble paste-like cement-compound. Thus a separate layer of the cement isifirst laid upon the hacks of the celluloid or other cellulosio supports. .T he cement very slowly partially penetrates the cellulose support, becomes amalgamated therewith tis-part of its body, and also forms a superimposed thin layer or film ofcement which remains upon the surface as a. layer of very. great adhesiveness.

When therefore the two cement-coated backs of the two films' are brought into contactand pressed together thetwo supports be-- come amalgamated, as if only one strip. by means of the two extremely thin layers of cellulose paste, which eventually dry hard owing to gradual penetration ofthe solvent through thev support. and the assistance of heat during passing of the united films through a suitable drying chamber.

, This cellulose paste is of the kind often termed .dope but is stiffer than the fiowable variety used for casting film supports. The composition of the cement depends upQn the composition of the transparent support. If for example the support is of nitro-cellulose (commonly termed celluloid) the cement is made from dry cuttings of that maticular solvent will vary according to the' terial dissolved'in amyl-acetate, which is a comparatively heavy slow-drying solvent. It the support is one of' the non-fiam type, comprising one of the many varieties of cellulose acetate, the cement'is made from dry cuttings of-that material dissolved in the heaviest solvent of that material. The parparticular make of .cellulose-acetate used; the variety of non-flam forms of cellulose are numerous, and a different slow-drying solvent is usually necessary with each variety.

It is usual in mixing cellulose cements to incorporate a large proportion of al quicklyevaporating solvent even where a slow-drying solvent is also used; but in the invention I do not use or incorporate any of such higha ly-volatil'e solvents but instead rely entirely upon solvents that will slowly penetrate and.

amalgamate the films and willtake considerable time to dry ofi. Y p

During application of the thick pastelike cement to the backs of the two films they are suitably held and carried by va cementing registering and uniting machine,

which draws the two .films from two supplyspools, positions them with fair accuracy by means of sprocket wheels the teeth of which engage with the perforations of the films;

the cement is applied in a thin layer lor vfilm by Scrapers or rollers as the filmsv travel through this machine; and iinallythe twov films are brought into near juxtaposition,

and are 'then engaged by pins which accurately register the'two component images, the pins, exactly filling the -perforations 'of the films, and then the two films are clamped between reciprocating clamping blocks by which they are squeezed together Vand completely` united. Owing to the slow-drying and very adhesive cement used a comparatively light Apressure only is needed for this part of the operation. y

The mechanical methods of carrying'out this part of the process, and machines therefor, are described in my Patent No. 1,169,- 098 and of application Serial No. 756,168,

i filed'December 15, 1924.

One such machine is illustrated in Fig.k

l1. The stiff cellulose paste or dope is contained in the hoppers A from which it falls through a slit B, the thickness oi" the layer of paste applied to each film beingexactly determined' by a scraper knife C controlled.

i by a screw c. Each film is drawn over a spreading table 'D and the slits B are arranged suiciently far backfrom the point The method of uniting the two iiclms previously described has the advantage that the films to'be united remain comparatively dry and stout whereas if a fluid solvent such as methyl-alcohol alone is employed the films become soft and liable to distortion. The twd-color positive film is n ow complete and ready for exhibiting.

If it is desired to vary the physical vcondition of the colloid imagesthe filml may .i

be' passed through abath containing a very small proportion of glycerine to keep thebody of' the colored colloid more supple and less hard. 1 Or the bath may contain a very small proportion of chrome alum to harden the surface. I prefer, however, to apply to the'two surfaces of the completed filmA an extremely thin layer of a colloid varnish in which the glycerine and/or chrome alum are incorporated. This is effected by passing the vfinished film through a bath of these combined ingredients, then pasti air jets which blow through the perforations to keepy themv clear of varnish, and finally drying the finished film.

The methods herein described for manufacturing a two-color cinematograph yseries of film-positives from ready-colored filmmaterial, as a single film built-up from twoA films that' are cementedv back-to-back (cellulose-to-cellulose) cwith the two component;y

images located upon the two outer faces of the central sup ort and in accurate register, produce a hn with strong solid marf gins of full thickness, without any trouble-.

some weakened`fold, with less labour and fewer operations, without waste due to trimming, with a much better joint, and without the troublesome operationsinvolved in dyeing the two sides with twodi erent colors after making the two prints, and represent considerable improvement upon the.

methods hithertov known and used.

What Iclaim as my invention and desire to protect by Letters Patent is 1. A 'two-colour positive cin'ematograph i Hlm comprising in its construction two transparent supports of, the exact width of the film, a layer of slow drying stiff cellulose cement paste by which the supports are joined together, a layer of coloured colloid with images printed in relief in silver salts on each support, and insoluble solid margins at each edge formed of the printed colloid to the full thickness of the film material. 2. The method of producing a twocolour positive oinematograph film which .consists in utilizing a\ transparent support coated 'With tvvo stripes of differently coloured colloid one coloured orange-red and the other vblue-green sensitized with silver salts print-Y ing thereon images in relief and printing the margins adjacent to the images torender them insoluble and solid lof the full thickness of the film, developing and finishing the images, severing the support into two lengt tudinally the exact width of the film and positive cinematograpb film which consists in printing and producing images in relief upon a double width transparent support in two parallel stripes of different coloured colloid sensitized with silver salts, submitting the margins at each side of the images to light to render them insoluble, severing the support longitudinally into two strips of exact width for the film and superimposing them upon two layers of cellulose paste by which they are united back to back.

5. In the production of a two .colour positive cinematograph film as in claim 1 subjecting the non-picture margins to a further exposure to light to render them in@ soluble and at the same timeprojecting the previously exposed picture portions of the film during the subsequent exposure by a covering mask which does not cover the maroiiis.

6. A two coloni' posit-ive cincuiatograph lilni as in claim l perforated along,T thc solid insoluble margins substantially as described.

ln testimony whereof I have hereunto set my hand.

.JOHN EDWARD. THORNTON 

